HELP PLEASE!!! Tohatsu M70B lower case removal

hello folks, i've started to take the lower leg off my outboard to check the impellor. the engine is brilliant but water outout seemed to drop lately. have only been running it on ear muffs the last three months, approx. 5 times. so hasn't picked up any rubbish and not sudden salt build up so figured it must be impellor. if i crank the hose up it increases the output so either i did not have enough pressure in the first place or all the lobes are off the impellor and water is getting by!

i have all 6 bolts off the lower case and the gear linkage split pin out but the case is not coming off easily. i don't want to focre anything so was hoping for some advice.

also, how hard is it to source parts for these motor now? its a 1994.

thanks

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

We use wedges and patience. Odds are the driveshaft is probably stuck in the crankshaft splines. When you reassemble, grease those splines. Just don't grease the tip of the shaft, or the grease could liquid lock, and prevent you from seating the shaft all the way.

You do need tons of water for muffs to work properly on those motors, so the pump may be OK, but if in doubt, of you know it's been a few years, install a new kit: Part# 3F3652311M, $100.66 MSRP, available from any dealer, including me.

Year is unimportant for servicing these, model/serial is everything. Many parts are still available for the 70B.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

If you are a Brit parts are available through your distributor. However, if they do not have them it can be up two months before they are available...In which case you might want to have Paul send them over to you.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

i'm having a hell of a time getting it off. any tips or trick you can recommend?

the parts are hard to source here in new zealand. a couple dealers couldn't be bothered but i got a price from someone eventually. not cheap!

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

We use wedges and patience. Odds are the driveshaft is probably stuck in the crankshaft splines. When you reassemble, grease those splines. Just don't grease the tip of the shaft, or the grease could liquid lock, and prevent you from seating the shaft all the way.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

well i've never quite experienced anything like that. one guy on each side prying with bars and my hitting a block of wood with the sledge hammer. i'm not kidding. we even had the trailer up on blocks to eliminate any absorbtion of the strikes. finally we got it moving, slowly. and then it came off.


all good. i need to do a bit of filing of the case and touch up the paint a wee bit. not sure when the guy had last done his impellor, i assume a long long time ago. all lobes there still though.


now the new problem. i snapped the brass water pipe just inside the grommet of the leg. how screwed am i? from what i can see in any exploded diagram the upper end of the pipe is flanged. can i get it out? can i get a new one in?? not sure i can patched the pipe in any way.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

The part is available for about $20.00. You will need to specify what driveshaft length you have. You will need to pull the power head to change it.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

thanks paul. hard to find any info online about a job like that. looking at the engine it looks like you only need to disconnect alot of linkages and then get at the 6(?) bolts attaching the engine to the leg. are these bolts likely to be seized and snap? any other curve balls i can expect? i'm not far off making the decision to take it to the professionals at this point.

i imagine taking the old pipe out and putting the new one in is the easiest part.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

well i put the water pump back together and greased the splines. when i tried to put the leg back on it went in far enough that could turn the propellor and see the engine was turning so slines were definately engaged. but it seemed to want to only go on about a cm or two. so i found some long bolts and creeped it slwly on but i could feel it was tight.
anyhow, when i run it now there is a slightly harmonic or trumpet like sound. i am sure there are gaps in the housing on the lower leg from the force needed to get it off. but is it likely i have damaged the bearings or something up where the splines fit in from all the force of taking it on and off with such force? and if i have is there a kit avaiable for a rebuild as it seems like i have to take most of the outboard apart to get at that area?

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

if there is interference in the splines, you could have a twisted driveshaft. Otherwise, it was just very cruddy. Either way, it should just slide back together. Forcing it is never a good idea. If you damaged the bearing or associated parts in the LU (doubtful you damaged the crankshaft bearings), you may need to take the LU down again.

It's not a good idea to grease the impeller; that lube will now go through the whole cooling system, and it might speed deterioration of the impeller. We neber re-use an impeller; if the wp comes apart, unless the motor is new, we install a new wp kit (not just a new impeller). Lasts longer, and pumps better, with the same labor.

Did you ever fix the broken water tube?

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

hi paul, i meant i greased the splines in the top of the driveshaft not down in the water pump, and i remembered not to greased the top surface like you said.

the driveshaft went back in easier then it came off, but still obviously alot of crud etc on the receiving end. i put the lower unit on just to see if everything is working ok after the trouble taking it off. i will look at a rebuilt/recon soon though so the lower unit will be coming off in a couple months.

my question is this sound i hearing. is it more likely a damaged bearing in the bottom of the motor, top of the driveshaft? or exhaust escaping out of one os the now not well sealed lower unit?

oh, and yeah i patched the water tube with an outer sleeve, until i get the powerhead off during the rebuild in a few months anyway. it seems alot of work to get at the top of the tube and not take advantage of the situation to recon the engine? its going to be alot of labour costs to get it to that stage.

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

and is there a recon kit or anything like that? or do you just order the parts you need when you know what you're dealing with once the engine is apart?

Re: HELP PLEASE!!! Tohatsu M70B lower case removal

fish_head_soup said:

and is there a recon kit or anything like that? or do you just order the parts you need when you know what you're dealing with once the engine is apart?

Click to expand...

Hard to say just what your sound might be. Possibly just leaking exhaust at the LU attachment, as you say.

There is a powerhead gasket set, but things like rings and pistons will need to be decided upon after you disassemble everything and get out the ol' micrometers to see just how much wear is really present.